MY NOTES A proton is projected in the positive x direction into a region of uniform electric field E = (-5.00 x 105) i N/C at t = 0. The proton travels 6.60 cm as it comes to rest. (a) Determine the acceleration of the proton. magnitude m/s2 direction -Select- (b) Determine the initial speed of the proton. magnitude m/s direction -Select- (c) Determine the time interval over which the proton comes to rest